This invention relates to Automatic Teller Machines (ATMs). It is particularly concerned with the detection of fraud in such machines.
One function of an ATM is to dispense banknotes to a user. A standard ATM having the facility to dispense banknotes includes electronic control means in the form of a central processing unit (CPU) which is connected to a cash dispenser unit and a user interface device. The user interface device comprises a display unit, a keypad, a card reader and an output slot through which the cash dispenser unit dispenses banknotes to a user. As is well known, to operate such an ATM a user inserts a user's identity card into the card reader and then enters certain data, such as a personal identification number (PIN) and the quantity of currency required to be dispensed, by mean of the keypad. The ATM will then process the requested transaction, dispense banknotes extracted from one or more storage cassettes within the currency dispenser unit, update the user's account to reflect the transaction and return the card to the user.
One advantage of ATMs is that they operate without human supervision and can be located at sites away from bank premises. A drawback is that they are vulnerable to being tampered with for the perpetration of fraud or other types of theft. One of the more common methods of attack is to add or insert mechanisms into the ATM to prevent their standard operation and either capture the contents of a transaction or record confidential information.